Optical receiver modules used for receiving high speed (e.g., GHz) optical data signals propagating along an optical fiber are known to those of skill in the art. Typically within these optical receiver modules there is an optical detector electrically coupled to an amplifier circuit in such a manner that light from the optical fiber illuminates the optical detector, the optical detector generates photocurrent in response thereto, and the amplifier circuit amplifies this photocurrent. The optical qualities of the optical detector are typically determined at least in part by the material structure of the optical detector. For some ranges of wavelengths, the materials of choice for the optical detector are costly, and as such, semiconductor materials used for manufacturing the amplifier circuit and the optical detector are typically not the same.
Typically, the amplifier circuit, optical detector and associated decoupling capacitors are sourced separately. Thereafter, the optical detector, the amplifier circuit, decoupling capacitors, and a module housing are assembled to form an optical receiver. Typically, the housing is designed for easy coupling to an optical fiber. Because these modules are used for receiving high speed optical data, the length of bond wires used to connect the optical detector to the amplifier acts as an integral component of the high speed input stage to the amplifier. Thus, the module may be more or less sensitive to incoming optical signals, depending on an exact configuration and manufacture.
In manufacturing, manufacturers typically are unable consistently to achieve optimal optical operating characteristics for the assembled receiver modules because the wires coupling the detector to the amplifier circuit play an important role in the performance of the receiver module and are known to vary significantly in manufacture.
Furthermore, isolated testing of the amplifier circuit is not representative of final performance until tested with a detector coupled thereto. Thus, meaningful testing can only be conducted at the completed receiver module level.
Finally, the performance of the module or some subset of the entire assembly will also be dependent upon the value, position, and performance of the power supply decoupling capacitors. These capacitors are integrated into the module by the manufacturer and contribute to the difficulty of designing a manufacturable module.
As a result a need therefore exists to manufacture the receiver module in such a manner that facilitates testing of the receiver module as a complete system in order to eliminate effects that yield undesirable performance prior to selling thereof. Chip level integration is desirable for test and manufacture, however, optimum TIA and optical diode technologies are fundamentally different, and therefore do not easily allow monolithic integration.